The present invention relates to phase detectors, and more particularly to an infinite dynamic range phase detector which extends the dynamic range of a phase detector to any desired limit.
For characterizing the behavior of networks that will be stimulated by arbitrary signals and interfaced with a variety of other networks, network analyzers were developed to provide a complete description of a given network's behavior in the frequency domain. The parameters of the given network not only vary as a function of frequency, but are also complex variables in that they have both magnitude and phase. Network analyzers measure magnitude and phase as a function of frequency, from which impedance and transfer functions can be displayed. The measurements are accomplished through sine wave testing, i.e., a test sine wave signal is applied to the network under test and the fundamental of the output sine wave signal from the network is compared to a reference sine wave signal which is generally the test sine wave signal. In many network analyzers, such as the Model 8410 Series Network Analyzers manufactured by Hewlett-Packard Company of Palo Alto, Calif., for measuring phase a phase detector compares the reference signal with the output signal from the network being tested. If the phase of the output signal shifts further than .+-.180.degree., the phase detector output resets by flipping from one extreme, +180.degree., to the other, -180.degree.. For short duration measurements this dynamic range is generally adequate. But for measurements over extended frequency ranges what is desired is the total phase shift, not just the relative phase shift within a .+-.180.degree. range.
Also it is desired to know whether the phase shift is positive or negative. If the indication of phase shift is -10.degree., it is ambiguous as to whether the shift was actually +350.degree..